1. Field of the Invention
The present invention relates to a control apparatus of an air-conditioner. More specifically, the present invention relates to a control apparatus for protecting a compressor from an overloaded state.
2. Description of the Prior Art
One example of this type of contrcl apparatus of air-conditioner is disclosed, for example, in the Japanese Patent Laid-Open No. 126534/1985 laid-open on Jul. 6, 1985.
In this prior art, means for detecting a current value flowing through a compressor is provided, and a current-value signal from this detecting means is sampled every predetermined period. When a difference (a variation) in the current-value for each sampling exceeds a certain value, the value of the current flowing through the compressor is suppressed once to prevent the compressor from being overloaded.
In this prior art, whether or not the compressor is in an overloaded state is detected by detecting a variation in the value of the current flowing through a current path of the compressor. In such a detecting method, however, when the compressor is put in a so-called "locked state", such a locked state cannot be detected. Because, when the compressor is put in the locked state, an excessively large current only flows continuously and the variation of the current value is not so large.